Hydrochloric Acid → 5-Hydroxymethylimidazo[5,1-b]thiazole

Participants

Reaction Steps

To a solution of 0.929 g of the ethyl imidazo[5,1-b]-thiazole-5-carboxylate obtained in Preparation 9 in 20 ml of methanol was added 0.897 g of sodium borohydride, and the mixture was stirred overnight at room temperature. 2 ml of concentrated hydrochloric acid was added dropwise to the reaction solution with ice-cooling. The mixture was stirred for 10 minutes, and then concentrated to dryness under reduced pressure. The residue was dissolved in 50 ml of methanol, and concentrated to dryness again. To the residue were added 30 ml of an aqueous potassium carbonate solution (50 wt. %) and 30 ml of dichloromethane with ice-cooling. The mixture was stirred for 10 minutes, and then filtered to remove insoluble matters. The organic layer was separated, and the aqueous layer was extracted with dichloromethane (30 ml×2). The combined organic layers were dried over anhydrous potassium carbonate, and purified by flash column chromatography using silica gel, eluting first with ethyl acetate and then with a 20:1 mixture of ethyl acetate and methanol to give 0.628 g (yield 86%) of the title compound as light yellow crystals.

Provenance & Evidence